Evaluation of HPK and FBK silicon photomultipliers for TOF and PET applications

In time-of-flight (TOF) measurements, or positron emission tomography (PET) experiments where two gamma rays are emitted in coincidence, the time resolution of the photon detector is of primary importance. SIPMs are very promising devices for these applications, since their intrinsic response time is very short, typically less than 1ns. In practice, the actual timing resolution of SIPMs is affected by the area (capacitance) of the device, by the type of electronics used to pre-amplify the signal, by the dark count rate which is viewed as background noise, and other second order effects like cross-talk and after dark pulsing. In this work we report the characteristics of different samples of Hamamatsu Photonics (HPK) and Fondazione Bruno Kessler (FBK) SIPMs, with pixel size ranging from 40 to 100 micron. In particular, we have investigated the time response when stimulated with O(100) ps pulsed laser with a wavelength of 407nm. Finally, SIPM performances are compared with that of fast silicon PIN diodes characterized with the same setup.